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2018 Second Alert - SA005_HiPo05
A high pressure kick was taken whilst attempting to mill a restriction in the 4 ½” liner on Sakhiya 44. There were no floats in the string and the TDS was positioned a full stand above the rotary table. The topdrive upper (hydraulic) IBOP valve was was closed when the drillpipe pressure was 4,000psi but did not seal. The standpipe pressure eventually stabilised at 5,844psi. It was not possible to generate enough torque to close the manual IBOP at height from the manrider. The well was killed with the wait and weight method. The contingency plan was to shear the string if the standpipe started leaking.
Run float valves in all BHAs. A manual IBOP requires very high torque (7kftlbs) to close with 10kpsi internal pressure. Spaceout the TDS to be at an accessible height when milling so that if required this high torque can be applied to the manual IBOP. Include a kelly cock just above the rotary table when conducting “at-risk” operations ie perforations / milling / displacing to lower fluid weights. High zinc content IBOPs are not compatible with high chloride (salt) mud environments as dezincification can rapidly occur. If a restriction is observed in the casing / liner run slickline drifts and e-line logs to understand the cause of the restriction before swedging or milling

Category:Second AlertsDocument Type:Safety
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